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Wind Farm – Turbine Spacing • As the wind passes though a turbine energy is extracted causing the wind speed in the wake of the turbine to decrease. When several turbines are built near one another, as in a wind farm, it is important to separate the turbines appropriately to minimize these array losses. Spacing turbines too tightly leads to reduced performance and increased maintenance due to higher turbulence at the downwind turbines. • Turbine spacing is expressed in terms of the rotor diameter (RD) of the turbine in consideration. So, for instance, if a 77 m diameter rotor is used, then 2 RD means 2 x 77 m = 154 m = 505 ft. • Typically, turbines are spaced 5 to 10 RD apart in the prevailing downwind direction and 2 to 5 RD apart in the crosswind direction, when there is a strongly prevailing direction. • Spacing of 2-3 RD might be used along a ridge line. • Greater spacing will minimize the losses from each machine, but will reduce the number of machines that can be built in a site. • The setback distance from property lines is determined by local building codes, and typically takes the height of the structure into consideration, e.g. 1.5 times the turbine height. • Additionally, state noise policy will typically keep wind turbines about 3 times the hub-height from residences. • Ice throw: Ice is likely to accumulate on ridgemounted wind turbines, just as it accumulates on trees. The ice sloughs off as the blade flexes. For public safety, ridge-line winter trails may need to be moved away from the base of the tower to a distance of 2-4 times the blade-tip height, depending on the site. • EX: Need 4000 acres (4000 x 43,560 ft2 = 6.25 mi2) for placement of an 80 MW wind farm (about 30-35 turbines) including a 100’ x 100’ area around each turbine.
Effect of Wake • Extraction of energy results in an energy and velocity deficit, compared to prevailing wind, in the wake of a wind turbine. • Energy loss in the wake will be replenished over a certain distance by exchange of kinetic energy with the surrounding wind field. • Higher turbulence in the wind field accelerates energy and momentum exchange between the wake and prevailing wind. • Array losses are typically < 10% for turbines spaced 8-10 RD apart in prevailing downwind direction and 5 RD apart in cross-wind direction.
Off-shore Wind Farms • Smooth surface of oceans results in low surface roughness and thus low turbulence intensity and wind shear. • Higher low-level winds (lower hub heights acceptable) • Lower fatigue damage and longer turbine life • Wind velocity measurements at hub heights are not generally available so good estimates must be made.
Wind Turbine Siting • Siting is at the heart of conflicts regarding wind turbines • Key issue • How a turbine interacts with its immediate natural environment, including living things • What influences siting of wind installations? • Politics • Local politics and ad hoc associations have the greatest effect on the placement of wind energy installations • Not In My BackYard (NIMBY) opposition • Noise and shadows created by turbines • Homeowner opposition • Often consider the operation of large turbines to be incompatible with a residential area • Level of controversy depends on context of the siting • A small wind farm in rural Nebraska • Little controversy by local residents because the installation fits into the landscape • A small wind farm near a federal or state park • Significant level of opposition by local residents: turbines will spoil the pristine natural surroundings, kill birds, and discourage tourism
Wind Turbine Siting • Survey of opposition to wind energy found a common set of global issues with minor variation depending on local conditions • Three key points to remember when considering siting issues • A limited number of sites exist that are useful for wind turbines, as opposed to fossil fuel and nuclear facilities which easily fit into industrial settings • Wind turbines need high quality wind: it blows fast and often with minimal turbulence created by the surrounding landscape • Turbines are more effective the higher they are located above the ground, which further contributes to one of the biggest issues in windmill siting: disruption of the viewshed • Disruption of the viewshed is cited the most often by opposition to new wind installations • Local residents may resist the siting anyplace where turbines will be visible from a distance • Includes offshore development, especially along the Northeast coast of the United States • Some opponents object to any visible development of wind energy • Wind power does not suffer as does nuclear energy—while specific installations are often opposed, wind energy is generally considered to be a boon for the environment • (Turbine: 50m; Observer: 1.5m; Visual distance: 20mi)
Onshore vs. Offshore Siting • Both onshore and offshore siting is highly criticized for its effect on the view-shed • Destruction of pristine natural resources, reduction in tourism, and reduction in real estate values (opinions conflict on wind turbines’ effect on real estate values) • Onshore concerns • Wind turbines are assumed to and can: create noise, cast a significant shadow, and create a flicker effect when the sun shines through the turbine blades • These issues are easily avoided through careful planning and engineering. • Three dimensional modeling accurately simulates viewshed concerns, turbine shadow, and flicker • Turbine design and placement can ensure local residents are not disturbed by excessive noise • Offshore concerns • Commercial fishermen fear that turbine installation will interfere with the operation of commercial fishing nets and drags • In Danish offshore installations, drags are not allowed in the turbine area • In the proposed Cape Wind site off of Cape Cod, lines would be buried deep enough to allow them • Sport fisherman and whale watching operations fear the effects on marine life • The Danish installation (by far the most complete) has demonstrated: • Fish exist as they did previous to the turbine installations • The turbine installations create reefs, which add to the diversity and health of ocean life (takes time) • Once installation is complete, maintenance trips and any noise from the turbine operations disturb marine life no more than already present shipping operations • Concerns over coolant oil leaks into the surrounding ocean have also been addressed by some groups who plan to use a nontoxic gaseous replacement
Assessing a Wind Resource • Must have enough wind with the right characteristics • Identify a wind energy site (typically through wind resource maps) • Measure winds at the site for at least a year through all seasons (anecdotal information about a wind resource is insufficient) and make a long-term estimate • Shorter measurement periods may be adequate for site screening if sufficient data is available for correlation • For small wind: must have enough open space to reduce wind turbulence from nearby trees and buildings • For larger, multiple-turbine projects, a more extensive wind resource assessment using wind resource analysis and digital terrain models is necessary • Multiple measurement locations and heights • Wind direction • Shear and terrain roughness • Turbulence and turbine wake • For example: New England sites on ridgelines with tree cover introduce more complex terrain characteristics and require a wind resource assessment
Wind Turbine Siting • No simple answer to the question of where wind turbines will be welcome • Whether onshore or offshore, someone or something that somebody cares about will be affected • For example: opposition to drilling for oil in the Arctic National Wildlife Refuge • Only a small impact on humans but expected to disrupt a pristine natural area • Which uncertainties and social costs will people be comfortable accepting? • Who will be willing to accept these burdens in place of the status quo? • Who will receive the benefit?
Siting Considerations • Choosing a proper site for a wind turbine or farm is critical to a successful project • While the most important factors may vary from site to site, in any given instance a single factor can undermine the success of an otherwise superlative project • On the other hand, a site may be weak in one area but so strong in another area that it is viable, such as a site with very strong winds that is farther than normal from a transmission line • A viable wind energy site generally includes the following key factors • Attractive wind resource • Landowner and community support • Feasible permitting • Compatible land use • Nearby access to an appropriate electrical interconnect point • Appropriate site conditions for access during construction and operations • Aviation compatibility • Favorable electricity market
Landowner and Community Support • Landowner support • After a prospective wind site is identified, the project developer contacts landowners to discuss their interest in hosting one or more wind turbines • Most developers enter into a land lease arrangement with the landowner • Landowner grants the developer the right to access the property for studies related to permits, installing a meteorological tower to measure the winds, and ultimately to construct and operate a wind project in exchange for a payment to the landowner • For a multiple-turbine project where a large site is necessary to capture economies of scale, neighboring landowners are contacted to ensure that contiguous roads and electrical lines can be located between turbines • Community support • Critical to the success of a wind energy project, whether a large, multiple-turbine project or a single residential small wind turbine • Build support by helping the community to understanding and appreciate the environmental benefits and, for larger projects, tax revenue benefits and employment benefits during construction • Objections to the visibility of turbines represents the majority of objections from the local community • For smaller, community-scale projects advocated or sponsored by the community (a city or town) or hosted by a part of the community (a school or other commercial or industrial end user), community support may be the driving force for the project • For example, the Hull, MA, turbines and many of the other community-scaled wind developments throughout New England
Issues Affecting Public Acceptance of Wind Energy • Wind farm developers seek locations with the greatest wind resource and the smallest population • Mitigates human interaction and impact whenever possible • Uninhabited areas are scarce, such as in the New England states, for example • Many of the windy locations (including coastal areas and high elevations) are prized for their natural beauty and/or recreational value and are within sight of nearby communities, making community acceptance and support even more critical • Local impact vs. societal benefits • All forms of energy impact their surroundings, but society demands that its need for electric power plants be met • The benefits of wind power, on a regional and broader scale, are widely accepted and the population, as a whole, supports wind power when compared to the alternatives • After weighing the local impact versus the societal benefits, most communities embrace wind power proposals
Issues Affecting Public Acceptance of Wind Energy • Where local concern or opposition to wind energy exists, several factors may be in play • The idea of wind power is new to the local community • Misinformation about wind projects and their impact on local communities may be circulating, initiated by proponents and/or opponents • Without wind project experience, it is difficult for community members to know what to believe • As noted earlier, disruption of the viewshed is the complaint most often cited by local opposition to new wind installations • The American Wind Energy Association addresses most of these issues and others in "Wind Power Myths vs. Facts"
Cumulative Role of Wind Power • In addition to local concerns is concern over the broader context or cumulative role of wind power • If wind power currently comprises less than 1 percent of a region's electricity supply portfolio, it is too small to be significant; and the local community questions why it should host a facility • To other opponents, their concern is just the opposite: if one wind project is permitted on one scenic ridgeline, will all of the region's ridgelines and scenic vistas be open to wind farm development? • The reality lies somewhere between these two extremes • For example • New England’s power supply mix consists of a range of sources, powered by natural gas, oil, coal, nuclear, hydroelectric, waste-to-energy, and biomass sources • The contribution of each of these to the whole has, at one point in time, been negligible • Having only recently reached the point of commercial viability and reliability, wind power is now the nation's (and the world's) fastest-growing power source • In the near future, wind power will play an important role in New England’s electricity portfolio, perhaps similar to the 6% share now supplied by hydroelectricity (although it is not expected to contribute more than 10-15% of New England's portfolio)
Feasible Permitting • The permitting process for wind energy installations is unique to the permitting jurisdiction, the characteristics and location of the site, and technical details of the project • Studies that may be required to obtain permits may include, but are not limited to: • Avian and bat interaction • Wildlife • Plants • Wetlands • Archaeological and historical review • Stream crossing and soil disturbance • Aviation interaction • Local zoning • The permitting process typically has a public component where local residents have the opportunity to learn and comment about the project
Compatible Land Use • A viable wind project must be compatible with the site, the surrounding area, humans, and wildlife • Nearby residential development may make it difficult to maintain appropriate setbacks for zoning, sound, and public safety during construction and operation • Property value may diminish if converting it to host wind turbines is not its highest value use • Projects at higher elevations that are prone to icing must consider the proximity to the public during winter to ensure public safety • Compatibility with wildlife is typically addressed as part of permitting • Developers looking at prospective sites avoid major bird flyways and areas with known sensitive, threatened, or endangered species • Many land uses are fully compatible with wind energy • Farmland • Land parcels are large and sparsely populated • The amount of land taken out of production for the footprint of the wind turbines and ancillary roads is small when compared to the added revenue the landowner receives • For example: • Many of the higher elevation sites in New England that are ideal for wind energy projects are under conservation easements or are located on state or federally owned land not open to wind development • Other windy sites on mountain ridges or shorelines are highly valued for recreational/scenic purposes • Opportunities do exist where land use and wind projects can be compatible, e.g., farming, timber harvesting, ridgelines with little public use or not under conservation easements, and industrial or commercial properties
Proximity to a Nearby Transmission Interconnection • An optimal wind site may not be viable due to the cost and/or difficulty of interconnecting to the power grid • For small wind installations, proximity to the electrical interconnection point (the home or business electric meter) will minimize construction and wiring costs • For large projects, a nearby transmission line with the capacity to handle the power output of the wind installation is required • Power lines and substations can be costly and time consuming to permit and build • Costs depend on the area through which the line will run and the size of the line • The project developer will work with the local utility and/or the region's power pool operator to determine the feasibility of connecting to the nearest transmission line • The interconnection study will assess the impact of the wind energy generated and its electrical characteristics on the regional power grid • If modifications are necessary, the study will identify the technical and financial requirements • This rigorous and highly technical study is necessary to ensure continued reliability of the power grid as directed by the regional system operator (for Nebraska and the southern plains area this is the Southwest Power Pool, SPP)
Appropriate Site Conditionsfor Access During Construction and Operations • Ridgelines are attractive sites for larger wind energy installations to capture the more attractive wind resource at higher elevations • Roads to these sites can be marginal or nonexistent • Developers look for sites with existing adequate roads that can handle, or be modified to handle, the construction equipment needed to deliver the large turbine and tower components and the specialized crane to erect the turbine • If no roads exist, the economic impact of constructing a new road must be considered
Aviation Compatibility • Usually the highest objects in their area, wind turbines must be sited to avoid potential hazards to aviation • The Federal Aviation Administration (FAA) has established regulations applicable to large structures such as wind towers • Tower heights more than 200 feet, which includes most utility-scale wind turbines, require Federal Aviation Lighting and the filing of the FAA form 7460-1 Notice of Proposed Construction or Alteration • Each FAA region works with wind developers to design lighting requirements specific to that region and the site • The FAA is currently working to create a national standard for wind turbine lighting • Each FAA region would have the option to adopt these recommendations
Favorable Electricity Market • The economics of small wind projects, under a net metering configuration, are primarily based on the retail electricity rate that the wind energy displaces • In areas with high retail rates, the appropriate net metering legislation in place, and the right site, small wind can be a cost-effective supplement to a home or business's electricity supply • A large wind project's revenue (and, hence, its economic viability) depends on the region's wholesale electricity market • Attractive market prices and the ability to secure power purchase contracts for the energy from the wind project largely depend on the costs of the existing mix of electric supply sources in the market and the ability of this supply mix to meet the demand • For example, in New England, the supply mix is predominantly natural gas and nuclear, with lesser amounts of coal, oil, and hydroelectric • Wind will typically compete with supply sources that are more expensive and are used more immediately to meet the hourly fluctuations in demand; currently this tends to be natural gas • As natural gas prices continue to climb, the energy from wind will become more attractive from a cost perspective
Favorable Electricity Market • Different locations within the region's power pool command different wholesale prices for electrical energy • Due to certain locations' higher demand, a lack of sufficient generation capacity in that location, and constraints in the transmission system that limit the import of less expensive power from outside that location • For example, within the New England Power Pool, energy is most valuable in southwest Connecticut (not a good location for wind) and the greater Boston area (where small wind projects along the coast may be viable) and less valuable in locations such as Maine (which has ample wind energy potential) • Favorable wholesale market rules are critically important to the viability of a wind project • Rules for physical interconnection to the power grid and how the wind project works in concert with the power requirements of the grid (i.e., integration, balancing and scheduling, etc.) influence the value of the wind energy directly, and in some cases the cost or financial risk associated with operating the plant • The specific electric characteristics of a wind project and its ability to satisfy the local regions' power quality requirements (such as through voltage support and other ancillary services) are also important
Exercise 11 1). Typically, turbines are spaced how far apart in the prevailing wind direction? • 2 to 5 rotor diameters • 100 feet • 50 rotor diameters • 5 to 10 rotor diameters
Exercise 11 2). Typically, turbines are spaced how far apart in the cross-wind direction. • 2 to 5 rotor diameters • 100 feet • 50 rotor diameters • 5 to 10 rotor diameters
Exercise 11 3). A typical setback distance of a turbine from property lines or other structures is • half the turbine height. • 1.5 times the turbine hub height. • 5 to 10 times the turbine hub height. • not needed.
Exercise 11 4). The top reason that wind turbine installations are opposed is generally in regard to • noise produced. • disruption of the viewshed. • micro-weather concerns. • cost of operation.
Exercise 11 5). A viable wind energy site generally includes the following key factors (list all that may apply). • Access to an electrical interconnect point • Landowner and community support • Attractive wind resource • Feasible permitting • Site access during construction and operations
Exercise 11 6). Permitting for an installation may involve environmental or ecological impact estimates on • Wetlands • Birds • Plants • Bats • B. and D. • All the above
Exercise 11 7). Federal Aviation Lighting and the filing of the FAA form 7460-1 “Notice of Proposed Construction or Alteration” are necessary for turbines extending to or above • 200 m • an elevation of 1,500 feet above sea level • 200 ft. • only near airports
Exercise 11 8). The study done to determine the feasibility of connecting to the nearest transmission line, and assess the impact of the wind energy generated and its electrical characteristics on the regional power grid is called • an interconnection study • a power transfer study • a funding study • a line routing study
Exercise 11 9). The regional transmission authority that all Nebraska utilities are part of is • National Renewable Energy Laboratory, NREL • Midwest Independent Transmission System Operator, MISO • Federal Energy Regulatory Commission, FERC • Southwest Power Pool, SPP
Exercise 11 10). A large wind project's revenue, and hence its economic viability, depends on the region's wholesale electricity market. • True • False
Impacts on the Human Environment • Visual • The primary impact of wind power is visual as wind turbines must be exposed to the wind in prominent locations • It is impossible to quantify esthetic considerations • Public policy and planning governs whether a community is willing to accept a visual impact in return for clean power • FAA lighting • The FAA requires objects over 200 feet tall — i.e., all commercial–scale wind turbines — to be lit • Specific lighting requirements vary from site to site; lights may be red or white, constant or flashing • Property values and tourism • The Renewable Energy Policy project studied 25,000 property transactions in the viewshed of wind projects, compared them to similar sites and found no evidence of reduced property values • Noise • Wind turbines are relatively quiet; however, how sound carries depends on terrain and wind patterns • Wind turbines should be about three times the hub height or more from residences • The sound generated from wind turbines can be compared to the sound level of a refrigerator from about 300 ft • TV interference • Today’s fiberglass composite wind turbine blades are unlikely to cause any interference with broadcast signals unlike the former metal blades which caused “ghosting” • Compatibility with other human land uses • Wind turbines can be found around the world safely coexisting with many land uses, including schools, highways, hiking trails, and farms
Sound • The majority of wind installations are in quiet rural areas • “Receptors” may be sheltered from the wind • Topography may amplify sound • Sound perception is highly subjective • An acoustical consultant may be helpful
Comparative Noise Level • Rotor –three-bladed • Smoother flow • Configuration –upwind • Tower shadowing reduced • Blades –redesigned • Less vibration • Gearbox –nacelle soundproofing How loud is the sound from a utility-scale turbine? 45 decibels at 350 meters
Wind turbine noise (at 200 m) is as loud as your refrigerator heard from the living room
Shadow Flicker (Visual Pollution) • Occurs when the sun is low in the sky and the sunlight is interrupted by a rotating turbine blade • Flicker is a function of season, latitude, and time of day • It is a temporary phenomenon as the sun moves across sky • Flicker can be minimized by proper setbacks • The developer may negotiate a sight easement
Ice Shedding • Small pieces of ice may be thrown • Larger pieces of ice usually drop within a blade’s length from the tower–they are not thrown • Recommended setback is 1.5 x total height • Tens of thousands of turbines are installed worldwide, and there has been no reported case of injury
Safety • Turbines have tubular towers with locked doors; the exterior cannot be climbed • Blade throw is extremely rare today, even in a catastrophic failure • Setbacks of 3-5 rotor diameters are common • A turbine failed at Weatherford, OK, May 7, 2005 • Winds were light at the time • The tower snapped • No injuries occurred • The cause is under investigation • The turbine was engineered to international safety standards (Germanischer Lloyd, Det Norske Veritas) • This was an isolated incident
Property Values • Phoenix Economic Development Group study, October 2002 • “Views of wind turbines will not negatively impact property values. Based on a nation-wide survey conducted of tax assessors in areas with wind power projects, we found no evidence supporting the claim that views of wind farms decrease property values.” • Renewable Energy Policy Project (REPP) study, May 2003 • “The statistical analysis of all property sales in the view shed and the comparable community provides no evidence that wind development has harmed property values within the view shed. There is no valid empirical support for claims that wind development will harm property values.”
What Kills Birds? – Human Causes • Glass Windows Bird Deaths a year: more than 100 million • Dr. Daniel Klem of Muhlenberg College, studied bird collisions with windows over 20 yr., His conclusion: glass kills more birds than any other human-related factor • House Cats Bird Deaths a year: 100 Million • The National Audubon Society says 100 million birds a year fall prey to cats. Dr. Stan Temple of the University of Wisconsin estimates that in Wisconsin alone, about 7 million birds a year are killed by cats • Automobiles/Trucks Bird Deaths a year: 50 to 100 Million • Birds killed by cars and trucks on the nation's highways is 50-100 million a yr., National Institute for Urban Wildlife and U.S. Fish and Wildlife Service • Electric Transmission Line Collisions Bird Deaths a year: up to 174 million • U.S. Fish and Wildlife Service estimates millions of birds die each year as a result of colliding with transmission lines • Agriculture Bird Deaths a year: 67 million • Pesticides likely poison an estimated 67 million birds per yr., Smithsonian Institution. Cutting hay may kill up to a million more birds a year. • Land Development Bird Deaths a year: unknown • Suburban sprawl is a silent but deadly killer. The National Audubon Society says loss of bird habitat is the greatest threat to bird populations. • Communication Towers Bird Deaths a year: 4 to 10 million • U.S. Fish and Wildlife Service estimates that bird collisions with tall, lighted communications towers and their guy wires results in 4-10 million bird deaths a yr. • Stock Tank Drowning Bird Deaths a year: unknown • U.S. Fish and Wildlife Service biologists and other conservationists believe that large numbers of birds inadvertently drown in livestock water tanks. • Oil and Gas Extraction Bird Deaths a year: 1 to 2 million • The U.S. Fish and Wildlife Service reports that up to 2 million birds died landing in oil pits to bathe and drink in 1997. Netting has improved that situation somewhat. There are no overall estimates for the number of birds affected by oil and gas spills and oil and gas extractions (and transport) • Logging and Strip Mining Bird Deaths a year: unknown • Logging and strip mining destroy bird habitat. According to the National Audubon Society, habitat destruction is the leading cause of bird population declines. • Commercial Fishing Bird Deaths a year: unknown • The U.S. Fish and Wildlife Service and the Ornithological Council report that 40 thousand seabirds per year are killed in the Gulf of Alaska by long-line fishing operations. These same sources say long lining and gill netting kill large numbers of birds in other parts of the country as well • Electrocutions Raptor Deaths a year: more than 1,000 • Experts estimate that more than 1,000 hawks, eagles, falcons and owls are electrocuted on transmission lines and poles each year • Hunting Bird Deaths a year: 100 + million • According to the U.S. Fish and Wildlife Service, more than 100 million ducks, geese, swans, doves, shorebirds, rails, cranes, among others are harvested legally each year Curry & Kerlinger, LLC has compiled the following information from environmental organizations and government agencies. info@currykerlinger.com Dick Curry, 1734 Susquehannock Drive, Mc Lean, VA 22101, (703) 821-1404, rca1817@aol.com Paul Kerlinger, P.O. Box 453, Cape May Point, New Jersey 08212, (609) 884-2842
Wind Turbine Effect on Wildlife—Fluffy is Dangerous! • Bird mortality due to wind turbines became an environmental concern with an abnormally high number of bird fatalities at the Altamont Pass Wind Resource Area (ARWRA) in Northern California • The 5,400-turbine project in Altamont killed at estimated 800 to 1,300 birds a year • Prompted many studies on avian mortality due to wind turbines • Studies have since revealed that the bird mortality rate seen at Altamont is unusual and can be attributed to technology used during construction and poor site selection • It lies along the path of a major migration route where many raptors nest and hunt • For all combined species, data collected in the U.S. outside of California revealed an average 1.83 avian fatalities and 0.006 raptor fatalities per year • This compares favorably with mortality rates caused by window strikes and domesticated cats • A less understood phenomenon is bat fatalities due to tower and turbine blade strikes • In 2003, more than 2,000 bats were killed at a 44-turbine project in Thomas, West Virginia • Biologists have theories but no consensus on what causes bats to fly into towers and turbine blades • While wildlife interacting with wind turbines is an important issue, it is manageable through siting and technology—the key is to make sure it is managed • The argument against wind energy due to avian mortality is put into context by the Audubon Society, which states that global warming and its concurrent loss of habitat is the greatest threat to wildlife today • Wind energy generation’s potential in displacing greenhouse gas emissions makes it acceptable in this context
Avian Impact (no pun intended) *The magnitude of these risks at a particular site would be addressed in a Phase 1 Avian Risk study. Modern wind turbines kill on average one to two birds per turbine, per year.
Bats and Wind Power • Bat fatalities have recently become an issue in the wind power industry because fatalities have been documented at wind power sites where post-construction bird studies have been conducted • Because of these fatalities, various wildlife agencies and environmental organizations have become interested in determining whether a problem exists • Bat fatalities have been studied at nearly the same number of wind power facilities as have bird fatalities • Data are now available from more than a dozen wind plants across the U.S. Here's what we know about this issue: • The numbers of bats involved are small at most wind plants, although in Minnesota and Wyoming moderate numbers have been found • Many of the bats involved in collisions with wind turbines were apparently migrating • About seven species of bats have been documented to collide with wind turbines • Bats involved are primarily common, tree-dwelling bats with widespread geographic distributions • Endangered or threatened species have not been involved • Population impacts seem unlikely • Bat fatalities have not emerged as a significant issue at wind plants in Europe • Migrating bats may turn off their “sonar” causing them to fly into towers • Small numbers of bats also collide with communication towers
Finding Suitable Sites • 3. Sufficient Landowner Interest • Meet with landowners to gauge interest • Will the project be supported by the community? • Enough land to develop a project (approx 4000 acres for an 80 MW project) • Approx. 100 acres per turbine (1 acre = 43,560 ft.2 = 4,047 m2) Photo Credit: Alice Buschkamp
Moving Forward • Sites that meet the previous criteria now need: • A project company and funding • Cooperation Agreements with Landowners (initial land rights) • On-site wind data • Initiate fatal flaw review • Begin transition from prospecting into development Photo Credit: Alice Buschkamp
Turbine Layout Plan • What factors into a Turbine Layout Plan? • Setbacks applied to project acreage to obtain buildable area. • Within buildable area, wind resource and constructability used to determine turbine sites. • Landowners approve locations of turbines and access roads. • Other factors include microwave beam paths, environmental issues, pipelines, etc. • Final plan used to submit for permits.
Center Pivot Irrigators • You Can’t Always Avoid Center Pivots • Nebraska has more sprinkler irrigated land than any other state — 72% * • Look to avoid pivots where economically feasible. • Laredo Ridge had a handful of parcels where turbines ended up inside pivot. • * Source: http://cropwatch.unl.edu/web/cropswater/stategraph Photo Credit: Mark Grundmayer
